The Blackjacks are Dying

Wednesday

Jul 26, 2017 at 12:07 PMJul 26, 2017 at 4:07 PM

Shawnee News-Star Garden Article Wednesday June 7th 2017 Becky Emerson Carlberg Four squirrels, five turkeys, three crows, two bluebird and one indigo bunting formed this morning's orchestra. All of these are native year-round species found in Cross Timbers except one. The indigo bunting spends its winter in Central America. Early spring the long-distance migrants fly [...]

beckycarlberg

Shawnee News-Star Garden Article Wednesday June 7th 2017

Becky Emerson Carlberg

Four squirrels, five turkeys, three crows, two bluebird and one indigo bunting formed this morning's orchestra. All of these are native year-round species found in Cross Timbers except one. The indigo bunting spends its winter in Central America. Early spring the long-distance migrants fly only at night until they land in the USA and their summer quarters. Here they live in Cross Timbers, a lengthy patch of woodlands and prairies that extend from the southern edge of Kansas through central Oklahoma into north central Texas. Fondly known as Ecoregion 29, Cross Timbers forms the buffer zone between the eastern forests and the High Plains.

Over the centuries, post oaks and blackjack oaks have established themselves on upland sandstone areas. Due to the nature of these trees, harvest was difficult, lucky for them, and some old growth forests still remain with oaks 200 to 400 years old. Other oaks have multiple trunks originating from one base and may have stump sprouted from roots possibly 1,000 years old. Some Pottawatomie County residents still remember the large groves of mature oaks, but most have been eliminated in exchange for pastureland or development.

New Yorker Washington Irving (1783-1859) was a talented writer and wealthy city boy known for 'Rip van Winkle' and 'The Legend of Sleepy Hollow.' He traveled through Cross Timbers the fall of 1832 with a military expedition. One entry in his journal was dated November 1st 1832: 'a broken, hilly country covered with scrub oaks, with interlacing limbs as hard as iron and intersected by deep ravines of red clay, down which the horses fairly slide and scramble up the other side fairly as cats.' In his book (published1835) 'A Tour on the Prairies' he described the oaks in late fall as dried and brown in a miserable, dreary country with lower branches black and hard that would tear flesh from man and horse. He loved the place.

Henry Ellsworth accompanied Irving and noted he never saw a man more impatient to be out of Cross Timbers. The delicate cloth gloves Irving wore did nothing to protect his hands. His hat was constantly knocked off his head. Part of his overcoat was shorn off which he didn't catch until later. Not a happy camper. A ranger following the expedition commented that Irving left a trail of black material through the thickets.

The two species of oaks differ in several respects. Post oaks (Quercus stellata) are in the white oak group. Their leaves, shaped somewhat like strange Maltese crosses with a few additional lobes, have veins that end at the edge of each lobe. Acorns mature the end of one growing season. The word 'stellata' means star. If you look at the bottom of a leaf using magnification, you can see tiny white hairs that form little stars. Post oaks are the hardier of the two species.

Blackjack oaks (Quercus marilandica) are in the red oak group. Their leaves appear as three toed green claws with veins that extend beyond the leaf margins. It takes two years for their acorns to mature. The trunk is very dark brown compared to the lighter gray/brown of the post oak. This oak was first identified in wait for it Maryland.

Both red and white oaks form protective tyloses. Tyloses are growths produced by the water conducting vessels to block the spread of fungi and other pathogens up and down the tree. This defense mechanism offers the post oak greater protection against the fungus 'Biscogniauxia atropunctata' or Hypoxylon canker. The canker fungi can cause die-back that will be seen one or two years after severe drought. The white rot fungus destroys sapwood by breaking down the tree structural support system of lignin and cellulose. Sapwood lies between the bark and heartwood center. It is the living part of the tree that contains the water and food supply vessels needed to keep the tree happy, healthy, and alive.

Apparently the blackjack oak is more susceptible to invasion by 'B. atropunctata.' The tree begins to look sad, but the defining moment comes when the tan fungal stroma pushes off the bark and releases powdery spores. The cushion ages to a black patch, but the tree is compromised. If branches are infected, they can be pruned. 'Biscogniauxia' occurs naturally on the bark of oaks and even in the sapwood as a facultative parasite. But. if the tree is wounded, chemically damaged or under the environmental gun, its defenses may crumble and the fungi will take advantage.

To all oak owners, utility companies and the county, in an effort to preserve our Cross Timbers, please be careful when pruning our valuable post oaks and blackjacks. Disinfect your tools with 10% bleach solutions. Contaminated tools can easily spread the fungal spores to cut branches or skinned trunks during moist spring conditions. Blackjack oaks in particular are disappearing as entire stands die. Unlike Washington Irving, I happen to love my blackjacks and post oaks.

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